Bug 581

Summary:	gluUnProject multiplies matrices in wrong order
Product:	[JogAmp] Jogl	Reporter:	Wade Walker <wwalker3>
Component:	core	Assignee:	Sven Gothel <sgothel>
Status:	RESOLVED FIXED
Severity:	normal	CC:	sgothel
Priority:	---
Version:	2
Hardware:	All
OS:	all
Type:	---	SCM Refs:	cbc77718f01a8190e1a8aa0e9afdc2a3a3403358 7f85501bd448afc9ba52f6abbe5f049d673d824d
Workaround:	---

Description Wade Walker 2012-05-07 22:00:34 CEST

gluUnProject() and gluUnProject4() in ProjectFloat.java and ProjectDouble.java multiply the model and projection matrices in the wrong order.

This seems to be because calls to gluMultMatricesf() and __gluMultMatricesd() (which multiply in column-row order) were replaced by calls to FloatUtil.multMatrixf() and FloatUtil.multMatrixd() (which multiply in row-column order).

This problem appeared in RC6, and was first reported by user "lukej" on the forum at http://forum.jogamp.org/Problems-with-gluUnProject-td3954975.html.

Comment 1 Sven Gothel 2012-05-11 22:48:14 CEST

<http://jogamp.org/git/?p=jogl.git;a=commit;h=cbc77718f01a8190e1a8aa0e9afdc2a3a3403358>

Fix regression of commit 
<http://jogamp.org/git/?p=jogl.git;a=commit;h=de2b129a56335262a44a05541a3ab2e35668cc6e>:
ProjectFloat Matrix Multiplication of gluUnProject(..) impl.

ProjectFloat's previous gluMultMatricesf(..) used row-major order,
but the replacement multMatrixf(..) uses column-major order (like OpenGL, ..).

Note: The replaced 'gluMultMatrixVecf' by multMatrixVecf() already
           used column-major order.

Fix: Reverse the arguments of matrix multiplication
    m1 x m2 -> m2 x m1

Comment 2 Sven Gothel 2012-05-12 04:13:49 CEST

<http://jogamp.org/git/?p=jogl.git;a=commit;h=7f85501bd448afc9ba52f6abbe5f049d673d824d>

Added further unit test w/ actual gluUnProject(..) usage.

Remark: FloatUtil's multMatrixf(..) does column-major multiplication,
i.e. expect the linear matrix layout to be in column order.

In case the implementation does not follow the above statement (you find a bug),
pls re-open this bug report.